The therapeutic advantages of the application of intermittent compression to injured or afflicted areas of the body to prevent venous stasis and reduce the risk of emboli are well recognized by the medical profession today. However, the automatic systems available for such purposes tend to be bulky, expensive, and allow limited mobility of the patient during use. It also is well known that the application of cold and compression following injury or certain surgery is beneficial.
Present devices available for such purposes generally require manual pumping or movement of the chilled fluid from its source to recycle the fluid as it is warmed at the body interface. During such recycling, there is a concomitant deviation of pressure, thus, in effect, rendering the process less efficient than desired. Moreover, in certain instances, for example, when the compress device is applied to a shoulder, additional help is required to cycle the system. In addition, with these devices additional compression is sometimes applied with an elastic wrap over the cold device. In this event, the amount of compression is unknown, and may be excessive, and the applied compression is static rather than intermittent or pulsating as preferred.
In commonly assigned copending application Ser. No. 737,402, filed Jul. 29, 1991, now U.S. Pat. No. 5,230,335, the therapeutic value of simultaneous application of cold and compression to an injured body part such as a knee is set forth. The invention disclosed therein, sold by the common assignee under the name "Aircast Cryo/Cuff," provides a simple and economical device that applies therapeutic cold and a first level of compression to the limited area of the knee that needs the therapy while using means for controlling the compression below the knee to a second predeterminable amount to minimize the constriction of venous circulation in the lower leg.
That invention includes a cuff-shaped compress with a watertight inflatable chamber shaped to envelope the anterior and sides of the knee including particularly the suprapatella pouch and the area of the knee just below the patella. Those are the areas where posttrauma body fluids accumulate and where cold and compression are most needed. The cuff is economically fabricated from sheets of flat material and its novel design permits adjustable shaping so as to conform to the knee even when the knee and cuff are flexed at different angles. The cuff is held in place with an upper proximal strap and a lower distal strap that avoid the popliteal area and minimize constriction. When the cuff is applied to the knee, the straps are secured but not tightened. A first amount of compression is then supplied to the knee by inflating the cuff to a reasonably predeterminable amount which causes the cuff chamber to expand. The expansion tensions the straps and applies compression to the areas of the knee under the chamber.
The cuff normally is strapped in place when empty and is then inflated with ice water which is supplied by a tube or fluid conduit from a cooler or container that is elevated above the cuff and the cuff is pressurized by gravity. With this technique, the amount of compression is determined by the elevation of the container above the cuff.
With such a device, chilled water becomes warm as it remains in contact with the body through the body/compress interface during treatment. Conversely, high temperature fluids are cooled as time passes. Thus, the effectiveness of both high and low temperature fluid treatments diminishes with time. Periodically, the fluid must be drained from the device and a fresh supply of fluid must be added.
The water from the cuff is routinely recycled back to the cooler for rechilling by lowering the cooler below the cuff. During the time required for rechilling the water, the pressure in the cuff falls and this permits even any minimal pooling of blood that might occur in the veins to be flushed out.
U.S. Pat. No. 5,080,089 attempted to remedy this problem of varying temperature at the cuff/body interface by providing an apparatus which, in one mode, allowed nonambient temperature fluid from a remote reservoir to be continuously circulated under pressure through a cuff wrapped around the injury. In another mode, air at ambient temperature is placed under pressure in the cuff and the cuff is sealed to apply compression, but not cold, to the limb. This has the advantage of near constant temperature without having to raise and lower the cooler periodically to recycle the water. However, the system is rather complicated and utilizes complex components, and is incapable of applying simultaneous compression and cold.
It is thus an object of the present invention to overcome the disadvantages of the prior art by providing a simple method of automatically and efficiently recirculating the fluid between the compress and the container to maintain general continuity of temperature at the compress/body interface, while simultaneously applying intermittent compression of a predetermined magnitude.